Beam deflection electron discharge device



" Sept. 24, 1946.. c. R. KILGORE 2,493,215

BEAM'DEFLECTICN ELECTRON DISCHARGE DEVICE Filed March 6 1942 Y INVENTOR.

George R1171 Igor-e.

ATTORNEY Patented Sept. 24, 1946 BEAM DEFLEGTION ELECTRON- DISCHARGE VICE.

George Ross. Kilgore, Verona, N. J.,. assignor to Radio Qorporatiom of America, a corporation of Delaware Application March 6,1942, Serial Na 433,580

12G1aims. 1

My invention relates to electron discharge devices, particularly to' the beamdeflection type, suitable for use as amplifiers at ultra high frequencies:

Electron discharge devices utilizing beam deflection have not proved particularly satisfactory as amplifiers at high frequencies. One of the reasons for this seems to be that beam deflection devices as usually constructed have low trans-- conductance and therefore require very high output impedance to give appreciabl gain. Con venticnal output circuits used have been of rela ti-vely low impedance and therefore have allowed little or no gain.

It is", therefore; an object of my invention toprovidean improved electron dischargedevice of the beam deflection type suitable for use at high frequencies:

A further object of my invention is to provide such a device which is particularly suitable foruse as an amplifier;

The novel features which I believe to be characteristic of my invention areset forth with particularity in the appended claims; but the invention itself" will best be understood by reference tothe following description taken in connection with theacom-panyi-ng drawing in which Figure I is a longitudinal schematicsection of one form of electron discharge device made according to my invention and its associated circuit", and- Figures 2, 3 and 4 are schematic sections of modi fications of anelectron discharge device utilizing'my invention and their associated circuits.

In accordance with my invention I" propose toutilize a high impedance output circuit which renders a beam deflection electron discharge device capableof use as an amplifier: In one'form of' myinvention I provide a specific construction of deflecting electrodes which increases thetransconductance of the tube, and alsoan output electrode system of high impedance, thereby materially improving devices or this type and ren-- dering them suitable 'for use as amplifiers at ultrahigh frequencies.

In Figure I is shown a tube made according to my invention and having an envelope to in which is mounted a cathode I l for supplying a beam of electrons and heated bythe heater f2; The cathode is positioned to. register with apertured electrodes in the deflecting electrode system mounted within the tubular member ['3' supporting: the partitions l4 and [5 having: aligned apertures W and 1'5. A third partition I9" is provided an aperture l9" and positioned between partitions I 5 and F9 are defiecting'electrodes' l6 and IT for deflecting electrons across aperture W.

An output system comprises the inner tubular member t8. and outer tubular member l3 closed at one end by means of partition I8','so that the tubular members l8 and f3 form with the closure member l- '8" a closed quarterwave concentric line resonant cavity tank system, the beam of electrons being deflected across the aperture H! to induce radio frequency voltages and currents within the resonant cavity circuit in passing through the apertur l9 across th gap H!" between partition [9' and the inner tubular member l8: in amanner now well understood} Thisform of circuit has very high impedance. Thesecondary emission is suppressed by receiving electrons within, the inner tubular member 18'. Because electrons are collected along the length of the tubular member I8' a heavy current can be absorbed, A radiator or coupling loop 20 extends through aperture l3" in member [3 and contacts the inner member 18. The input signal is applied by means of input transformer 22 connected between electrodes l6 and H, the po-' tentials for the various electrodes being provided by means of the potential. source 21.

In this arrangement the output and input electrodes are completely shielded from each other and. from, the input and output circuits.

For maximumimpedanc the ratio of diameter of. the inner, and. outer conductors should be approximately 9. to 1. The impedance increases as the. diameterv of the outer conductor is increased until the diameter is a large fraction of the. wavelength. For very high impedance output I propose increasing the inner and outer conductors until the diameter of the outer conductor is roughly one-eighth of. a wavelength or oneeighth A. Thus by continuing the anode into the inner cylinder and utilizing this as the inner conductor of. a quarter wave concentric. line tank circuit, I provide an amplifierv tube which utilizes beam deflection and which is particularly suitable for use. as. an. amplifier.

In Figure2 Iishow an improved form of my invention which is particularly suitable for use at ultra high frequencies and which in addition has high initial transconductance, thus further improving its use as an amplifier.

In this arrangement the envelope 3%) contains the indirectly heated cathode 3| of concave form (heater not shown) for providing a converging beam of electrons which is received by the collector electrode 32. Surrounding the cathode and shielding a pair of, deflecting electrodes is a cylindrical' member 3'3 having transverse partitions 34 andv 35 provided with aligned apertures 34 and 35. The deflecting electrodes 36 and 31 converge toward the aperture. 35. I have found with this construction and by utilizing a curvature of radius of the cathode of one-half the length of the deflecting electrodes that the transconductance of the device can be made very high. In the arrangement shown the collector electrode system includes the collector 32 supported by means of the leads 38 preferably arranged in a circle and- 3 electrically connected to the inner tubular member 39, forming with the outer tubular member 48 and elements H and M a resonant cavity-tank circuit of quarter-wavelength, thus providing high impedance. The wall 4! and the transverse partition 35 are capacity coupled so that the end of the quarter-wave concentric line tank circuit is closed for radio frequency voltages and currents, except for aperture 35. Thegap between the lip 32' and the collector 32 permits the radio frequency field to be induced within the resonant cavity tank circuit in a manner now well known when a modulated stream of electrons passes a gap of this kind. The transmission line or. the next succeeding amplifier is coupled to the resonant cavity by means of th coupling loop 42. The input circuit may be provided by means of the Lecher wire system 43. A potential source 44 is provided for the various electrodes.

- A still further form of my invention is shown in Figures 3 and 4. Here the combined envelope and shielding cup 54 of more or less rectangular cross section supports at one end the cathode 50 indirectly heated by means of the cathode heater 5|, the converging beam of electrons being directed between the converging electrodes 52 and 53 through an aperture 51' in the outer tubular member 51 toward the inner tubular member 58 serving as the collector. End-closure members 51" and 58' seal the ends of members 58 and 51, thus providing a concentric line resonant cavity tank circuit, The inner member 58 is insulatingly supported from wall 58' by insulating busing 58" to permit a difference of constant potential between elements 51 and 53. In order to provide a closed evacuated envelope and at the same time to permit diiferent voltages to be applied to the tank and to the shielding cup 54, the two sections of the device may be joined by means of insulating collar 63 sealed to the cup 54 and to the extension 59 on the outer tubulaur member 51. The leads and supports 52' and 53 of the deflecting electrodes are sealed by means of beads 55 and 56 in the cup-shaped member as are the leads to cathode 50. The output may be taken off by means of the conductor 6| sealed through the outer tubular member 51 by means of seal 6|. The input signal is supplied by means of input transformer 62 and the necessary biasing voltages by means of voltage source 63.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having a cathode for supplying a stream of electrons, an output electrode system in the path of said beam of electrons and including an inner conducting member surrounded by an outer hollow conducting member and forming therewith a resonator, tubular shielding means positioned between the oathode and the output electrode system, and a pair of apertured transverse elements within said tubular shielding means and positioned between the cathode and the output electrode system, and a pair of deflecting electrodes positioned between said aperture transverse elements and between 4 which the path of said beam extends to said output electrode system. 7 I

2. An electrondischargeldevice having a cathode for supplying a beam of electrons, an output electrode system in the path of said beam of electrons and including an inner tubular conducting member surrounded by an outer hollow conducting member and forming therewith a resonator, tubular shielding means positioned between the cathode and the output electrode system, and a pair of apertured transverse elements within said tubular shielding means and positioned between the cathode and the output electrode system, and a pair of deflecting electrodes positioned between said apertured transverse elements and between which the path of said beam extends to said output electrode system, said inner tubular member lying in the path of the beam to receive electrons passing through the apertured element adjacent said output electrode system within the interior of the inner tubular conducting member.

3. An electron discharge device including a cathode for supplying a beam of electrons, an output electrode system in the path of said beam of electrons and including an inner conducting member surrounded by an outer hollow conducting member and forming together a resonator, said resonator having an element provided with an aperture through which the path of said beam extends, and deflecting electrodes positioned between said cathode and the element provided with said aperture and between which the path of said beam of electrons extends toward said aperture, said cathode having a concave emitting surface and said deflecting electrodes having surfaces converging toward each other in the direction of travel of said electrons from the cathode to the output electrode system,

4. An electron discharge device including a cathode for supplying a beam of electrons, an

output electrode system in the path of said beam of electrons and including an inner conducting member surrounded by an outer hollow conducting member and forming together a resonator, said resonator having an element provided with an aperture through which the path of said beam extends, and deflecting electrodes positioned between said cathode and the element provided with said aperture and between which the path of said beam of electrons extends toward said aperture, said cathode having a concave surface and said deflecting electrodes having surfaces converging toward each other in the direction of travel from the cathode to the output electrode system, the radius of curvature of said cathode surface being equal to one-half the length of the deflecting electrodes. l Y

5. An electron discharge device having an envelope containing a cathode for supplying a beam of electrons and a collector electrode for receiving said beam of electrons, an apertured element positioned between the cathode and the collector electrode'and having an aperture aligned with said collector electrode, and deflecting electrodes positioned between the cathode and the apertured element and between which the path of said beam ofelectrons extends, a conductor outside said envelope'electrically connected to said collector electrode and; a second conductor surrounding said first conductor, and forming therewith a quarter-wave resonator, and conducting means extending inwardly from the second conductor and closely adjacent the wall, of the envelope adjacent the apertured element and forming therewith for high frequency voltages and currents a closed wall having an aperture.

6. An electron discharge device having an envelope containing a cathode for supplying a beam of electrons and a collector electrode for receiving said beam of electrons and having a conductor extending through the wall of said envelope, an apertured element positioned between the cathode and the collector electrode closely adjacent the envelope wall and having an aperture aligned with said collector electrode, and deflecting electrodes positioned between the cathode and the apertured element between which the path of said beam of electrons extends, an elongated conducting member outside said envelope and connected to the conductor of said collector and a second elongated conducting member surrounding said first elongated conducting member and forming therewith a quarter-wave resonator, and a conducting plate extending inwardly from the second elongated conducting member closely adjacent the wall of the envelope adjacent the apertured element and forming therewith for radio frequency voltages and currents a closed wall having an aperture, and means connecting and closing the ends of the elongated conducting members remote from said envelope.

7. An electron discharge device having an envelope containing a cathode for supplying a beam of electrons, and a cup-shaped collector electrode for receiving said electrons, a shielding system for said cathode and extending toward said collector electrode and provided with a pair of transverse apertured elements with the apertures in alignment, a pair of deflecting electrodes positioned between said apertured elements and between which the path of the beam of electrons extends, the apertured element adjacent said collector electrode being placed closely adjacent the wall of said envelope, an inner tubular conducting member extending axially of said collector electrode externally of said envelope and electrically connected to said collector electrode, and an outer tubular member surrounding said inner tubular member and forming therewith a quarter-wave resonator, the end of said quarterwave resonator being closed adjacent the envelope by means of a transverse member capacity coupled to the apertured element adjacent the wall of said envelope to provide a closed wall for radio frequency voltages and currents induced in said concentric line tank circuit.

8. An electron discharge device including a cathode for supplying a beam of electrons and an output electrode system for receiving said electrons, said output electrode system comprising an inner conductor for collecting the electrons and an outer conductor coaxial with and surrounding said inner conductor and forming therewith a resonator, the outer wall of said resonator having an aperture through which the path of said beam of electrons extends and deflecting electrodes between the cathode and the aperture for deflecting said electron beam across said aperture, and means surrounding and supporting said cathode and said deflecting electrodes and insulatingly secured to said outer tubular member adjacent said aperture.

9. An electron discharge device including a cathode for supplying a stream of electrons and an output electrode system for receiving said electrons, said output electrode system comprising an inner conductor for collecting the electrons and an outer tubular conductor coaxial with and surrounding said inner conductor and forming therewith a resonator, an aperture in the outer wall of said resonator through which the path of said beam of electrons extends and deflecting electrodes between the cathode and the aperture for deflecting said electron beam across said aperture, and means surrounding and supporting said cathode and said deflecting electrodes and insulatingly secured to said outer tubular conductor adjacent said aperture, said cathode and deflecting electrode supporting element comprising a substantially cup-shaped member, the open end of which extends toward said output electrode system and extensions on the outer tubular conductor around said aperture extending toward the cup-shaped member, and an insulating collar connecting the open end of said cup-shaped member and said extension together providing a closed envelope for the cathode and deflecting electrodes.

10. An electron discharge device including means for supplying a beam of electrons, an output electrode system in the path of said beam of electrons and including an inner tubular conducting member surrounded by an outer tubular conducting member and forming a quarter-wave resonator, said output electrode system having an element provided with an aperture through which the path of said beam extends toward said inner tubular conducting member and deflecting electrodes positioned between the beam supplying means and the element provided with said aperture, the ratio of diameter of the outer tubular member to the inner tubular member being 9 to 1.

11. An electron discharge device including a cathode for supplying a beam of electrons, an output electrode system in the path of said beam of electrons and including an inner conducting member surrounded by an outer hollow conducting member and forming together a quarter-wave resonator, said resonator having an element provided with an aperture through which the path of said beam extends, and deflecting electrodes positioned between said cathode and the element provided with said aperture and between which the path of said beam of electrons extends toward said aperture, the ratio of the diameter of the outer conducting member to the inner conducting member being 9 to 1.

12. An electron discharge device including means for supplying a beam of electrons, an output electrode system in the path'of said beam of electrons and including an inner tubular conducting member surrounded by an outer tubular conducting member and forming therewith a quarter-wave concentric line resonator, said output electrode system having an element provided with an aperture through which the path of said beam extends toward said inner tubular conducting member, and deflecting electrodes positioned between the beam supplying means and the element provided with said aperture, the ratio of diameter of the outer tubular member to the inner tubular member being 9 to 1, the diameter of the outer tubular conducting member being approximately one-eighth the wavelength of the operating frequency.

GEORGE ROSS KILGORE. 

